Merck Manual

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Merkel Cell Carcinoma

(Neuroendocrine Skin Carcinoma; Primary Small Cell Skin Carcinoma; Trabecular Cell Carcinoma; APUDoma of the Skin; Anaplastic Skin Cancer)


Vinod E. Nambudiri

, MD, MBA, EdM, Harvard Medical School

Reviewed/Revised Dec 2023
Topic Resources

Merkel cell carcinoma is a rare, aggressive skin cancer that tends to affect older White people. Diagnosis is by biopsy. Treatment typically is determined by staging.

Lymphatic spread is common.

Symptoms and Signs of Merkel Cell Carcinoma

Skin lesions are typically firm, shiny, flesh-colored or bluish-red, and nodular. Their most characteristic clinical findings are rapid growth and absence of pain and tenderness.

Although Merkel cell carcinoma can affect any part of the skin, it is most common on sun-exposed areas (eg, face, upper extremities).

Diagnosis of Merkel Cell Carcinoma

  • Biopsy

Diagnosis of Merkel cell carcinoma is by biopsy.

Most patients have metastatic disease at presentation, and the prognosis is poor.

Treatment of Merkel Cell Carcinoma

  • Determined by staging

Treatment of Merkel cell carcinoma is determined by cancer staging and typically includes wide local excision, often followed by radiation therapy, lymph node dissection, or both.

Systemic therapy (eg, with avelumab, pembrolizumab, retifanlimab, or another programmed death receptor 1 [PD-1] inhibitor or conventional chemotherapy) may be indicated for metastatic or recurrent cancer.

Prevention of Merkel Cell Carcinoma

Because Merkel cell carcinoma is associated with ultraviolet (UV) exposure, a number of measures are recommended to limit exposure.

  • Sun avoidance: Seeking shade, minimizing outdoor activities between 10 AM and 4 PM (when sun's rays are strongest), and avoiding sunbathing and the use of tanning beds

  • Use of protective clothing: Long-sleeved shirts, pants, and broad-brimmed hats

  • Use of sunscreen: At least sun protection factor (SPF) 30 with broad-spectrum UVA/UVB protection, used as directed (ie, reapplied every 2 hours and after swimming or sweating); should not be used to prolong sun exposure

Drugs Mentioned In This Article

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